Project is carried out at two levels, in vivo and in vitro. In vivo includes a long range program of chemical carcinogenesis using a modified Peraino protocol. Acetyl aminofluorene (AAF) was fed to weanling male and female rats for 2 weeks only, at three levels, 0.015, 0.030, and 0.045% in semi-purified diet containing 30% casein. Tumor incidence, enzyme altered foci, an thymidine autoradiographs noted at various times in groups receiving 0.05% phenobarbital or basal diet, or partial hepatectomy at age 28 days during AAF feeding, total number of groups equals 29. (Still in progress). In vitro studies are focussed on primary liver cell cultures from rats at various ages, fasting and fed, or following partial hepatectomy. Four hepatoma cell lines in serial culture are used in parallel studies. Measurements emphasize amino acid and K-ion transport with various media and hormone combinations. A computer program has been utilized to quantitate the respective contributions of high Km and low Km systems based on initial velocities of uptake at varying substrate concentrations. Other measurements include assays for cyclic AMP, tyrosine aminotransferase and ornithine decarboxylase. The entire complement of newly synthesized soluble proteins labeled in culture with 35S-methionine with no hormone and hormone combinations is separated by 2-dimensional electrophoresis, and a computer program has been developed to quantitate the radioactivity of 101 individual spots based on autoradiography and microdensitometry.